This conspicuously brandless device, of Chinese manufacture, is for sale through multiple listings on Amazon, with prices ranging from $10.66 up to $20.95. The one I bought cost $14.99 with free Prime shipping, and came from CyberTech with fulfillment by Amazon itself. Besides the actual instrument, the package included a padded blue nylon zipper pouch, a four page instruction booklet in passable English, and about 24″ of 1cm-wide sparkly reflective tape.

In recent years my prejudice against Chinese tools has been proven wrong over and over again, and the DT-2234C+ is no exception. Frankly, this is a fantastic little tool, at a fantastic price, that gets the job done without breaking the bank. Is it cheap? Sure it is, in both common senses of the word. But is it worth every penny of its rock-bottom price? Again: Yes. A couple times over.

To make a measurement, the tool requires a rotating surface with a reflective area that is smaller than its non-reflective area. The special sparkly-flake tape included is nice for this purpose, but it is not strictly necessary; I got equivalent readings using common aluminum foil tape and plain white grip tape. In many cases, in fact, the tape was not necessary at all. To measure the speed of a fan, for instance, it was sufficient to simply point the meter at the spinning blades, take a reading, and divide by the number of blades.

The DT-2234C+ has a 5-digit LCD display with 3/4″ tall letters, and a range of 1 – 99,999 RPM. To 1,000 RPM it has a resolution of 0.1 RPM, and above that of 1 RPM. It claims an accuracy of ±0.05%, or to within 50 RPM at its upper limit of 99,999, which I did not have any handy means of testing. The DT-2234C+ has a minimum sampling time of 0.8 seconds, which will be higher at very low speeds (i.e. below 60 RPM), and a useful maximum range of about two feet. It also includes a memory function button that cycles through minimum, maximum, and last available readings from the last sampling period. It measures about 5×3×1″ and, with a 9V battery installed, weighs just a bit under 6 oz.

My use, so far, has consisted mainly of comparing the real speeds of various nominally-equivalent case fans so I can swap out the underperforming coolers, and for this purpose the DT-2234C+ has proven completely satisfactory. Since I haven’t been able to test its accuracy, I still hesitate to recommend it for work that requires reliable absolute readings. But for this kind of relative comparison-based testing, this little unit is a value that’s hard to beat.

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and makezine.com. My work has also appeared in ReadyMade, c’t – Magazin für Computertechnik, and The Wall Street Journal.

I’ve got one of these and they’re great little tools. Use it a lot for the lathe and mill to set/measure speed. Sometimes a little tricky to get a reliable signal – mine seems to like about a 50% black/white ratio in the signal, so make sure to cover sufficient area with the tape. The supplied tape is kinda diffusely reflecting so alignment isn’t as critical. I’ve found that sticking a small lens on the front allows you to measure a much smaller area since it focuses the laser spot.

These are cheap enough that I’ve seen people cannibalise them and mount them permanently to a mill or lathe spindle. I opened mine up once – if I remember, it was a single large micro (possibly an ATMega) doing everything.

I think it’s a bit disingenuous to imply that your only object to Chinese tools is the quality. Yes, they often produce some sub-par tools. But even the good tools are usually produced exploitatively (e.g. below a living wage, producing tons of pollution, etc).

Sean Ragan

This is a good point, and something I didn’t consider at all when I wrote this.

asciimation

I ended up making my own tachometer (using an Arduino of course) as I could never find one of these cheap ones that would go as high as I needed (150000 rpm) unfortunately.

To test it at lower speeds at least try measuring a mains powered asynchronous AC motor. The speed is fixed to the mains frequency so that should be reasonably accurate I think.

rocketguy1701

+1 for a build your own. Not just because of the DIY factor, but it’s an obtainable goal for the moderately electronically literate. Arduino, photo sensor and source, and some signal processing code, good to go.

How can I buy this product in UAE(Dubai) and what the accuracy of this product.
Thanks

Arshad

Steve

Best to buy a quality instrument for accuracy and long term reliability, See Compact Instruments web site, they have been manufacturing high quality laser tachometers for years

Christopher

I got one and they are really good. I had to send it to a NIST calibration lab, because we work with precision parts and calibration certificates are mandatory on every tool we use, and the NIST calibration lab issued a Certificate of Calibration. They are wonderful .